This might be a bit boring for a ThisNext recommendation, but anyone who's ever used a planer for a while has had the blades get chipped. It happens really easily too, a little bit of sand or steel stuck onto the surface of the wood you're planing will do it, and then you don't get that perfectly smooth surface you seek. It's just good to have an extra set of blades handy, especially if you switch frequently between dimensioning work and fine finish work.